1. Field of the Invention
The present invention relates to a machine and a method for identifying paper quality, to be more precise, paper material.
2. Description of the Related Art
One method to discriminate genuine from counterfeit about sheets, such as banknotes, for example, is performed by judging as to whether or not the material of sheets are proper. As to well known in the art, there is a technique of identifying the paper material, based on optical scanning of lattice shading patterns of the paper, which is caused by fibrous structure of the paper (e.g. JP8-180189A discloses those techniques). Another technique in the art is to identify the paper material according to the difference of the time required for transmitting sheets, which is caused by the difference of the frictional force corresponding to each paper material (e.g. JP11-139620A discloses those techniques).